Although normal E.coli cells can synthesize all the amino acids, some mutants called amino acid auxotrophs, are unable to synthesize specific amino acids and require the addition of that amino acid to the culture medium for optimal growth. In addition to their role in protein synthesis, specific amino acids are also required in the biosynthesis of other nitrogenous cell products. Consider the three amino acid auxotrophs that are unable to synthesize glycine, gjlutamine and aspartate, respectively. For each mutant what nitrogenous cell products, other than proteins, would fail to be synthesized.
The question really becomes, "What are glycine, glutamine and aspartate used to synthesize in the cells"?
If we know what glycine is used to produce, and glutamine is used to produce, and aspartate is used to produce, then we can easily answer the question because in these auxotrophs, they can't manufacture these simple amino acids.
Glycine: Glycine is a precursor of porphyrins. I don't know ...
This solution explains how glycine, glutamine and aspartate are respectively used to synthesize in the cells.